位置感知是移动应用的一项独特功能。移动设备用户无论走到哪里都随身携带自己的设备，因此为您的应用添加位置感知功能可给用户带来更加契合环境的体验。
代码示例
GitHub 上的 ApiDemos 代码库包含相关示例，展示了如何在地图上使用位置：
Kotlin
- MyLocationDemoActivity：使用“我的位置”图层，包括运行时权限
- LocationSourceDemoActivity：使用自定义
LocationSource - CurrentPlaceDetailsOnMap：查找 Android 设备的当前位置，并显示该位置上相应地点（商家或其他地图注点）的详细信息。请参阅有关在地图上显示当前地点详情的教程。
Java
- MyLocationDemoActivity：使用“我的位置”图层，包括运行时权限
- LocationSourceDemoActivity：使用自定义
LocationSource - CurrentPlaceDetailsOnMap：查找 Android 设备的当前位置，并显示该位置上相应地点（商家或其他地图注点）的详细信息。请参阅有关在地图上显示当前地点详情的教程。
使用位置数据
提供给 Android 设备的位置数据包括设备的当前位置（结合使用多种技术精准确定）、移动的方向和方式，以及设备移动范围是否超出了预定义的地理边界（或称地理围栏）。根据应用的具体需求，您可以从以下位置数据使用方式中进行选择：
- 我的位置图层提供了一种在地图上显示设备位置信息的简单方式。它并不提供数据。
- 建议通过 Google Play 服务地理位置 API 发出所有位置数据编程请求。
- 您可以使用
LocationSource接口提供自定义位置信息提供程序。
位置权限
如果您的应用需要访问用户的位置信息，您必须向应用添加相关的 Android 位置权限来请求权限。
Android 提供两种位置权限：ACCESS_COARSE_LOCATION 和 ACCESS_FINE_LOCATION。您选择的权限决定了 API 所返回位置的精确度。
android.permission.ACCESS_COARSE_LOCATION- 允许 API 返回设备的大致位置信息。该权限提供根据位置信息服务推测的设备位置信息，如介绍大致位置信息精确度的文档中所述。android.permission.ACCESS_FINE_LOCATION- 允许 API 利用包括全球定位系统 (GPS) 在内的可用位置信息提供程序以及 WiFi 和移动数据流量尽可能精确地确定位置。
向应用清单添加权限
如果应用只需大致位置信息即可正常运行，请向应用的清单文件添加 ACCESS_COARSE_LOCATION 权限：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myapp" >
...
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
...
</manifest>
不过，如果需要确切位置信息，请向应用的清单文件同时添加 ACCESS_COARSE_LOCATION 和 ACCESS_FINE_LOCATION 权限：
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.myapp" >
...
<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>
<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>
...
</manifest>
请求运行时权限
Android 6.0 (Marshmallow) 引入新的权限处理模型，简化了用户安装和升级应用的过程。如果您的应用以 API 级别 23 或更高级别为目标平台，便可使用这种新权限模型。
如果您的应用支持这种新权限模型，并且设备搭载的是 Android 6.0 (Marshmallow) 或更高版本，用户无需在安装或升级应用时授予任何权限。应用必须在运行时通过检查确认其是否具备必要的权限，如果没有，则请求相应权限。系统会向用户显示一个对话框，请求授予权限。
为提供最佳用户体验，请务必在上下文中请求权限。如果位置信息对于应用正常运行至关重要，则您应该在应用启动时请求位置权限。一种较好的做法是显示一个热情的欢迎界面或向导界面，让用户了解必须授予权限的原因。
如果应用需要的权限仅用于执行其部分功能，您应该在应用执行需要该权限的操作时请求位置信息权限。
应用必须以适当方式处理用户不授予权限的情况。例如，如果特定功能需要该权限，则应用可以停用该功能。如果该权限对于应用正常运行至关重要，应用可以停用其所有功能，并通知用户需要授予该权限。
以下代码示例利用 AndroidX 库检查权限，然后启用“我的位置”图层。之后，通过实现支持库中的 ActivityCompat.OnRequestPermissionsResultCallback 来处理权限请求的结果：
Kotlin
// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.example.kotlindemos
import android.Manifest
import android.annotation.SuppressLint
import android.content.pm.PackageManager
import android.location.Location
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import androidx.core.app.ActivityCompat
import androidx.core.app.ActivityCompat.OnRequestPermissionsResultCallback
import androidx.core.content.ContextCompat
import com.example.kotlindemos.PermissionUtils.PermissionDeniedDialog.Companion.newInstance
import com.example.kotlindemos.PermissionUtils.isPermissionGranted
import com.google.android.gms.maps.GoogleMap
import com.google.android.gms.maps.GoogleMap.OnMyLocationButtonClickListener
import com.google.android.gms.maps.GoogleMap.OnMyLocationClickListener
import com.google.android.gms.maps.OnMapReadyCallback
import com.google.android.gms.maps.SupportMapFragment
/**
* This demo shows how GMS Location can be used to check for changes to the users location. The
* "My Location" button uses GMS Location to set the blue dot representing the users location.
* Permission for [Manifest.permission.ACCESS_FINE_LOCATION] and [Manifest.permission.ACCESS_COARSE_LOCATION]
* are requested at run time. If either permission is not granted, the Activity is finished with an error message.
*/
class MyLocationDemoActivity : AppCompatActivity(),
OnMyLocationButtonClickListener,
OnMyLocationClickListener, OnMapReadyCallback,
OnRequestPermissionsResultCallback {
/**
* Flag indicating whether a requested permission has been denied after returning in
* [.onRequestPermissionsResult].
*/
private var permissionDenied = false
private lateinit var map: GoogleMap
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.my_location_demo)
val mapFragment =
supportFragmentManager.findFragmentById(R.id.map) as SupportMapFragment?
mapFragment?.getMapAsync(this)
}
override fun onMapReady(googleMap: GoogleMap) {
map = googleMap
googleMap.setOnMyLocationButtonClickListener(this)
googleMap.setOnMyLocationClickListener(this)
enableMyLocation()
}
/**
* Enables the My Location layer if the fine location permission has been granted.
*/
@SuppressLint("MissingPermission")
private fun enableMyLocation() {
// 1. Check if permissions are granted, if so, enable the my location layer
if (ContextCompat.checkSelfPermission(
this,
Manifest.permission.ACCESS_FINE_LOCATION
) == PackageManager.PERMISSION_GRANTED || ContextCompat.checkSelfPermission(
this,
Manifest.permission.ACCESS_COARSE_LOCATION
) == PackageManager.PERMISSION_GRANTED
) {
map.isMyLocationEnabled = true
return
}
// 2. If if a permission rationale dialog should be shown
if (ActivityCompat.shouldShowRequestPermissionRationale(
this,
Manifest.permission.ACCESS_FINE_LOCATION
) || ActivityCompat.shouldShowRequestPermissionRationale(
this,
Manifest.permission.ACCESS_COARSE_LOCATION
)
) {
PermissionUtils.RationaleDialog.newInstance(
LOCATION_PERMISSION_REQUEST_CODE, true
).show(supportFragmentManager, "dialog")
return
}
// 3. Otherwise, request permission
ActivityCompat.requestPermissions(
this,
arrayOf(
Manifest.permission.ACCESS_FINE_LOCATION,
Manifest.permission.ACCESS_COARSE_LOCATION
),
LOCATION_PERMISSION_REQUEST_CODE
)
}
override fun onMyLocationButtonClick(): Boolean {
Toast.makeText(this, "MyLocation button clicked", Toast.LENGTH_SHORT)
.show()
// Return false so that we don't consume the event and the default behavior still occurs
// (the camera animates to the user's current position).
return false
}
override fun onMyLocationClick(location: Location) {
Toast.makeText(this, "Current location:\n$location", Toast.LENGTH_LONG)
.show()
}
override fun onRequestPermissionsResult(
requestCode: Int,
permissions: Array<String>,
grantResults: IntArray
) {
if (requestCode != LOCATION_PERMISSION_REQUEST_CODE) {
super.onRequestPermissionsResult(
requestCode,
permissions,
grantResults
)
return
}
if (isPermissionGranted(
permissions,
grantResults,
Manifest.permission.ACCESS_FINE_LOCATION
) || isPermissionGranted(
permissions,
grantResults,
Manifest.permission.ACCESS_COARSE_LOCATION
)
) {
// Enable the my location layer if the permission has been granted.
enableMyLocation()
} else {
// Permission was denied. Display an error message
// Display the missing permission error dialog when the fragments resume.
permissionDenied = true
}
}
override fun onResumeFragments() {
super.onResumeFragments()
if (permissionDenied) {
// Permission was not granted, display error dialog.
showMissingPermissionError()
permissionDenied = false
}
}
/**
* Displays a dialog with error message explaining that the location permission is missing.
*/
private fun showMissingPermissionError() {
newInstance(true).show(supportFragmentManager, "dialog")
}
companion object {
/**
* Request code for location permission request.
*
* @see .onRequestPermissionsResult
*/
private const val LOCATION_PERMISSION_REQUEST_CODE = 1
}
}
Java
// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.example.mapdemo;
import android.Manifest.permission;
import android.annotation.SuppressLint;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.GoogleMap.OnMyLocationButtonClickListener;
import com.google.android.gms.maps.GoogleMap.OnMyLocationClickListener;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
import android.Manifest;
import android.content.pm.PackageManager;
import android.location.Location;
import android.os.Bundle;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import androidx.core.app.ActivityCompat;
import androidx.core.content.ContextCompat;
import android.widget.Toast;
/**
* This demo shows how GMS Location can be used to check for changes to the users location. The "My
* Location" button uses GMS Location to set the blue dot representing the users location.
* Permission for {@link android.Manifest.permission#ACCESS_FINE_LOCATION} and {@link
* android.Manifest.permission#ACCESS_COARSE_LOCATION} are requested at run time. If either
* permission is not granted, the Activity is finished with an error message.
*/
public class MyLocationDemoActivity extends AppCompatActivity
implements
OnMyLocationButtonClickListener,
OnMyLocationClickListener,
OnMapReadyCallback,
ActivityCompat.OnRequestPermissionsResultCallback {
/**
* Request code for location permission request.
*
* @see #onRequestPermissionsResult(int, String[], int[])
*/
private static final int LOCATION_PERMISSION_REQUEST_CODE = 1;
/**
* Flag indicating whether a requested permission has been denied after returning in {@link
* #onRequestPermissionsResult(int, String[], int[])}.
*/
private boolean permissionDenied = false;
private GoogleMap map;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.my_location_demo);
SupportMapFragment mapFragment =
(SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@Override
public void onMapReady(@NonNull GoogleMap googleMap) {
map = googleMap;
map.setOnMyLocationButtonClickListener(this);
map.setOnMyLocationClickListener(this);
enableMyLocation();
}
/**
* Enables the My Location layer if the fine location permission has been granted.
*/
@SuppressLint("MissingPermission")
private void enableMyLocation() {
// 1. Check if permissions are granted, if so, enable the my location layer
if (ContextCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION)
== PackageManager.PERMISSION_GRANTED
|| ContextCompat.checkSelfPermission(this, permission.ACCESS_COARSE_LOCATION)
== PackageManager.PERMISSION_GRANTED) {
map.setMyLocationEnabled(true);
return;
}
// 2. Otherwise, request location permissions from the user.
PermissionUtils.requestLocationPermissions(this, LOCATION_PERMISSION_REQUEST_CODE, true);
}
@Override
public boolean onMyLocationButtonClick() {
Toast.makeText(this, "MyLocation button clicked", Toast.LENGTH_SHORT).show();
// Return false so that we don't consume the event and the default behavior still occurs
// (the camera animates to the user's current position).
return false;
}
@Override
public void onMyLocationClick(@NonNull Location location) {
Toast.makeText(this, "Current location:\n" + location, Toast.LENGTH_LONG).show();
}
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions,
@NonNull int[] grantResults) {
if (requestCode != LOCATION_PERMISSION_REQUEST_CODE) {
super.onRequestPermissionsResult(requestCode, permissions, grantResults);
return;
}
if (PermissionUtils.isPermissionGranted(permissions, grantResults,
Manifest.permission.ACCESS_FINE_LOCATION) || PermissionUtils
.isPermissionGranted(permissions, grantResults,
Manifest.permission.ACCESS_COARSE_LOCATION)) {
// Enable the my location layer if the permission has been granted.
enableMyLocation();
} else {
// Permission was denied. Display an error message
// Display the missing permission error dialog when the fragments resume.
permissionDenied = true;
}
}
@Override
protected void onResumeFragments() {
super.onResumeFragments();
if (permissionDenied) {
// Permission was not granted, display error dialog.
showMissingPermissionError();
permissionDenied = false;
}
}
/**
* Displays a dialog with error message explaining that the location permission is missing.
*/
private void showMissingPermissionError() {
PermissionUtils.PermissionDeniedDialog
.newInstance(true).show(getSupportFragmentManager(), "dialog");
}
}
“我的位置”图层
您可以使用“我的位置”图层和“我的位置”按钮向用户显示他们在地图上的当前位置。调用 mMap.setMyLocationEnabled()，在地图上启用“我的位置”图层。
以下示例展示了“我的位置”图层的简单用法：
Kotlin
// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.maps.example.kotlin
import android.annotation.SuppressLint
import android.location.Location
import android.os.Bundle
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import com.google.android.gms.maps.GoogleMap
import com.google.android.gms.maps.GoogleMap.OnMyLocationButtonClickListener
import com.google.android.gms.maps.GoogleMap.OnMyLocationClickListener
import com.google.android.gms.maps.OnMapReadyCallback
import com.google.android.gms.maps.SupportMapFragment
import com.google.maps.example.R
internal class MyLocationLayerActivity : AppCompatActivity(),
OnMyLocationButtonClickListener,
OnMyLocationClickListener,
OnMapReadyCallback {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_my_location)
val mapFragment =
supportFragmentManager.findFragmentById(R.id.map) as SupportMapFragment
mapFragment.getMapAsync(this)
}
@SuppressLint("MissingPermission")
override fun onMapReady(map: GoogleMap) {
// TODO: Before enabling the My Location layer, you must request
// location permission from the user. This sample does not include
// a request for location permission.
map.isMyLocationEnabled = true
map.setOnMyLocationButtonClickListener(this)
map.setOnMyLocationClickListener(this)
}
override fun onMyLocationClick(location: Location) {
Toast.makeText(this, "Current location:\n$location", Toast.LENGTH_LONG)
.show()
}
override fun onMyLocationButtonClick(): Boolean {
Toast.makeText(this, "MyLocation button clicked", Toast.LENGTH_SHORT)
.show()
// Return false so that we don't consume the event and the default behavior still occurs
// (the camera animates to the user's current position).
return false
}
}
Java
// Copyright 2020 Google LLC
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package com.google.maps.example;
import android.annotation.SuppressLint;
import android.location.Location;
import android.os.Bundle;
import android.widget.Toast;
import androidx.annotation.NonNull;
import androidx.appcompat.app.AppCompatActivity;
import com.google.android.gms.maps.GoogleMap;
import com.google.android.gms.maps.OnMapReadyCallback;
import com.google.android.gms.maps.SupportMapFragment;
class MyLocationLayerActivity extends AppCompatActivity
implements GoogleMap.OnMyLocationButtonClickListener,
GoogleMap.OnMyLocationClickListener,
OnMapReadyCallback {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_my_location);
SupportMapFragment mapFragment =
(SupportMapFragment) getSupportFragmentManager().findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
}
@SuppressLint("MissingPermission")
@Override
public void onMapReady(GoogleMap map) {
// TODO: Before enabling the My Location layer, you must request
// location permission from the user. This sample does not include
// a request for location permission.
map.setMyLocationEnabled(true);
map.setOnMyLocationButtonClickListener(this);
map.setOnMyLocationClickListener(this);
}
@Override
public void onMyLocationClick(@NonNull Location location) {
Toast.makeText(this, "Current location:\n" + location, Toast.LENGTH_LONG)
.show();
}
@Override
public boolean onMyLocationButtonClick() {
Toast.makeText(this, "MyLocation button clicked", Toast.LENGTH_SHORT)
.show();
// Return false so that we don't consume the event and the default behavior still occurs
// (the camera animates to the user's current position).
return false;
}
}
启用“我的位置”图层后，“我的位置”按钮会显示在地图的右上角。用户点击该按钮时，镜头将设备的当前位置（若已知）显示为地图的中心。设备处于静止状态时，地图以小蓝点指示该位置；处于移动状态时则以 V 形指示该位置。
下面的屏幕截图显示了右上角的“我的位置”按钮和地图中心的“我的位置”蓝点：
您可以通过调用 UiSettings.setMyLocationButtonEnabled(false) 禁止显示“我的位置”按钮。
您的应用可以响应以下事件：
- 如果用户点击“我的位置”按钮，您的应用会收到来自
GoogleMap.OnMyLocationButtonClickListener的onMyLocationButtonClick()回调。 - 如果用户点击“我的位置”蓝点，您的应用会收到来自
GoogleMap.OnMyLocationClickListener的onMyLocationClick()回调。
Google Play 服务地理位置 API
Google Play 服务地理位置 API 是向您的 Android 应用添加位置感知功能的首选方法。借助地理位置 API，您可以：
- 确定设备位置。
- 监听位置变化。
- 在设备处于移动状态时，确定交通方式。
- 创建并监控预定义的地理区域（称为地理围栏）。
通过地理位置 API，您可以更方便地构建功能强大的位置感知应用。与 Maps SDK for Android 类似，地理位置 API 也是作为 Google Play 服务 SDK 的一部分进行分发。如需详细了解地理位置 API，请参阅 Android 培训课程让您的应用具备位置感知能力或地理位置 API 参考文档。Google Play 服务 SDK 中已添加了相关代码示例。